Engine Starting Troubleshooting Suggestions

[PremiumBikes]

HI MotoBike Fam,

I acquired a motorized bicycle that had starting issues. The bike will not start.

1) Motor has great compression

2) Replaced Carb with a Brand New Carb

3) Replaced Spark Plug with Brand New spark Plug

4) Replaced CDI with brand new CDI

5) Replaced Magneto with a brand new Magneto.

The Spark plug sparks great when testing out of the crankcase.

There is fuel getting into the combustion chamber as I can see the mist on the spark plug. There is also fuel mist coming out of the exhaust.

Even with Quick Start Engine Starter, the engine will not fire.

The Magnet in fine with the correct polarity and position.

I am totally out of ideas now. Any further suggestions would be welcomed before I pull out my hair.

Thanks!

 

[allen standley]

The Magnet in fine with the correct polarity and position.
If this Rotating magnet was replaced / re-installed upside down, you will get spark--but at the wrong time, creating a NO Start situation as you described.

 

[PremiumBikes]

I double checked the magnet position and it is in the suggested spot. At TDC the indicator on the magnet is at the 2'oclock position.

This seems correct as if it was installed incorrectly, the indicator notch would be at 11 clock.

One thing I was thinking was that when I installed the new Magneto, I did not sand paper the surface that touches the engine. On Youtube, a guy says to sand it when there is lacquer on there but there was no lacquer from the factory so I left it as is.

Should I be sanding this regardless on a new magneto?

 

[allen standley]

Hmmm... @ this point I'm perplexed. If you are getting a spark sanding the contact surface is not the problem. -Kill switch is designed to short across when pressed so, again If you are getting A strong Spark That's not the problem either? Pull the magneto out, be sure the blue wire is soldered proper into the coil. The White wire (if you have one) should be removed and carefully capped/taped. Curious, did you replace all above mentioned parts at the same time? You also say a history of starting problems...
My conclusion,
Weak Compression Pull cylinder head and look for scarring on walls. OR
Timing MUST be off. Replace Rotating Magnet, could have been cut wrong from the factory should be 1oclock @TDC.
Keep your post alive and see if others chime in with a fresh idea. I'll be watching your post for a positive result.

 

[PremiumBikes]

Thanks for the suggestions.

One thing I did not do is someth the blue/blue and black/black connections. I just used the clips that came on the ends of the wires to attach them.

Would this clip to clip connection suffice on these engineers or do they need to be soldered?

 

[allen standley]

Follow this thread may be helpful also.
https://motorbicycling.com/threads/...-have-spark-video-included.58424/#post-602610

 

[allen standley]

I always solder. never use those connectors. That could be the prob. follow up on the link I posted.

 

[allen standley]

Also don't use starter fluid in these engines it cleans the oil out of the rings and drys' em out
Real Bad Bad Bad for your cylinder.

 

[ZekeNoScooter]

It's been a while since your last update. Did you get er running? If so, what was the problem? Having same issues, same failed solutions, (replaced plug, carb, CDI was next). Made a setup to start it on a stand. Clutch in and turned the mashed l magnet with a drill. Unfortunately I visualized my clockwise/counter-clockwise wrong and was turning the motor over BACKWARDS!!! Can you guess? Yep. Fired right up.
Realized my error and killed it. Completely stunned. Looked up here on forum. Found nothing. (I'm bad at it anyway, searching). So I opened my mind to this abomination of physics. Epiphany! Switched the magneto leads to the CDI and bingo. Advance/retard depending on rotational direction. I hope this is my last bug. Been slowly building this thing for months. Gonna finally go ride it!